Impact
------
Due to the way Active Record handles nested query parameters, an attacker can use a specially crafted request to inject some forms of SQL into your application's SQL queries.

All users running an affected release should upgrade immediately. Please note, this vulnerability is a variant of CVE-2012-2661, even if you upgraded to address that issue, you must take action again.

Impacted code directly passes request params to the `where` method of an ActiveRecord class like this:

Post.where(:id => params[:id]).all

An attacker can make a request that causes `params[:id]` to return a specially crafted hash that will cause the WHERE clause of the SQL statement to query an arbitrary table with some value.

Releases
--------
The FIXED releases are available at the normal locations.

Workarounds
-----------
This issue can be mitigated by casting the parameter to an expected value. For example, change this:

Post.where(:id => params[:id]).all

to this:

Post.where(:id => params[:id].to_s).all

Patches
-------
To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset. We have also provided a patch for the 3.0 series despite the fact it is unmaintained.

Please note that only the 3.1.x and 3.2.x series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.

Credits
-------

Thanks to Justin Collins of Twitter for the backport to 2.3 and to the
following security researchers who reported the vulnerability and helped
us verify the fixes (in alphabetical order):